The story revolves around Raul, a boy who did not become a Hero, since the demon lord was already defeated just before his Hero exams. His dreams dashed, Raul spends his days working at a magic shop in the capital. One day, a part-time job seeker appears at the shop with an amazing résumé: 
Name: Phino 
Previous Occupation: Demon Lord Heir 
Motive: Because my father was defeated 
The work comedy revolves around this former Hero-in-training and the daughter of the demon lord.
 
(Source: Anime News Network)

I Couldn’t Become a Hero, So I Reluctantly Decided to Get a Job.